1. Field of the Invention
The present invention relates to a conveyance method for transporting a plurality of unprocessed/processed objects between an automatic transporting device and a semiconductor manufacturing device, the manufacturing device having a load port to/from which the objects are delivered from/to the automatic transporting device.
2. Background Art
In the inspection process of semiconductor devices, for example, a prober is widely used as an inspecting device for inspecting semiconductor wafers (the semiconductor waters will be simply referred “wafers”, after.). Normally, the prober includes a loader chamber and a prober chamber and performs to inspect the electric characteristics of a device in the form of a wafer. The loader chamber includes a carrier mount for mounting a carrier accommodating a plurality of wafers (e.g. 25 sheets), a wafer transporting mechanism (which will be also referred “arm mechanism” after) for transporting the wafers from the carrier mounting part one by one and a prealignment mechanism (which will be referred “sub-chuck” after) for carrying out pre-alignment for a wafer transported by the arm mechanism. Further, the prober chamber is equipped with a mounting table (which will be referred “main-chuck” after) that moves in all directions of X, Y, Z and θ while mounting a wafer thereon, an alignment mechanism for carrying out alignment of the wafer in cooperation with the main chuck, a probe card arranged above the main chuck and a test head interposed between the probe card and a tester.
Therefore, when inspecting the wafers, an operator firstly mounts a carrier having a plurality of wafers accommodated therein in lot unit, on the carrier mount in the loader chamber. Next, with the drive of the prober, the arm mechanism picks up the wafers in the carrier, one by one. Then, after carrying out pre-alignment for the wafer by the sub-chuck, the arm mechanism delivers the wafer to the main chuck in the prober chamber. In the loader chamber, the alignment for the wafer is carried out by the main chuck and the alignment mechanism. While index-feeding the wafer by the main chuck, the wafer after the alignment is brought into electrical contact with the probe card thereby to perform to inspect the designated electrical characteristics of the wafer. After completing the inspection of the wafer, the arm mechanism in the loader chamber receives the wafer on the main chuck and returns it to the original position. Thereafter, the operator repeats the above procedure in order to inspect the next wafer. On completion of inspecting all the wafers in the carrier, the operator exchanges the carrier for the next carrier and further repeats the above inspection for new wafers.
However, if a wafer to be inspected has a large diameter of, for example, 300 mm, it becomes almost impossible for an operator to handle a carrier having a plurality of such wafers because the carrier is remarkably heavy. Even if the operator can handle the carrier, the operator's carrying alone may be accompanied with a risk. Further, since the management about particles in a clean room has become severe with the hyperfineness of semiconductor devices, the automatization of manufacturing installations, such as carrier conveyer, is taking on importance increasingly in view of managing particles in the clean room. This requirement applies to not only a prober but also general semiconductor devices.
Additionally, due to the large-diameter and hyperfineness of a wafer, there is a jump in the number of devices to be formed in a single wafer, requiring a long period for completing a process, such as inspection, for one wafer Moreover, to process wafers in lot unit would cause the wafers after processing to stay in a prober until the processing operation will be completed in all of the wafers in the lot, thereby delaying a time for feeding the wafers in lot unit to a sequent process. Consequently, it becomes difficult to shorten TAT (Turn-Around-Time) in the production.
Therefore, it is desired to provide conveyance system and method for transporting objects to be processed, which enable automatization of the conveyance operation about the objects thereby to realize a reduction in the number of operators and which can shorten TAT about the objects.
On the other hand, since there is a recent tendency that the carrier becomes heavy for the wafers having large diameters thereby making it difficult and risky for an operator to handle such a carrier, Japanese Patent Publication (kokai) No. 10-303270 proposes a conveyance method that employs an automated guided vehicle (which will be also referred as “AGV” after) to transport the carrier thereby to allow wafers in the same lot to be delivered between the vehicle and an process installation, in carrier unit. With the adoption of this conveyance method, an operator's transporting a carrier is so automated that the above problem can be solved. In this method, when transporting wafers from an automatic transporting device to a process installation, such as semiconductor manufacturing device, it is carried out to make the carrier-destination “load port” number of a signal line of the communication interface accord with the “load port” number of the semiconductor manufacturing device thereby transporting objects to be processed, such as wafers, to a designated carrier mount, in carrier unit.
However, if one carrier is present in the semiconductor manufacturing device having the only load port, the next carrier cannot be loaded unless the previous carrier is unloaded from the semiconductor device as a result of completion of processing all the objects in this carrier. Thus, the operation for processing the objects comes to a standstill during loading and unloading the carrier, so that an improvement in the throughput of the system cannot be expected. While, if establishing new load ports in the semiconductor device, then a problem arises in the increase in footprint and also manufacturing cost There is the same problem when transporting a plurality of unprocessed/processed objects (wafers) between the AGV and the semiconductor manufacturing device via the load port.
Therefore, it is desired to provide a conveyance method for efficiently transporting a plurality of unprocessed/processed objects between the AGV and the semiconductor manufacturing device via the load port, without requiring an excessive space for an additional load port, thereby preventing the footprint and the system manufacturing cost from increasing. Additionally, it is desired to provide a centering device that can center an object to be processed certainly when transferring objects to be processed, one by one.
Further, due to the large-diameter and hyperfineness of a wafer, there is a jump in the number of devices to be formed in a single wafer, requiring a long period for completing various processing, such as inspection, for one single wafer. Therefore, even if the wafers in the same lot could be transported to a semiconductor manufacturing device, such as inspecting device in carrier unit by the AGV, the processing of wafers in lot unit would require considerable date and time while causing even the wafers after processing to stay in the semiconductor manufacturing device. Consequently, the time to feed the wafers in lot unit to a sequent process is delayed to that extent, so that it becomes difficult to shorten TAT (Turn-Around-Time) in the production.
Therefore, it is desired to provide conveyance system and method for transporting objects to be processed, which enable certain delivery of the objects to be processed, such as wafers, in sheet unit between an automatic transporting device and a plurality of semiconductor manufacturing devices and which enables parallel processing of the objects by the plural semiconductor manufacturing devices thereby realizing the abbreviation of TAT about the objects.
Further, as for the conventional centering method, the centering has been carried out by using an optical sensor, after picking up a wafer from a carrier through an arm mechanism and before executing the pre-alignment of the wafer. Therefore, there are problems that it takes a lot of time for centering a wafer and a lot of cost for the optical sensor for this centering.
Therefore, it is desired to provide a centering method for wafers, which eliminates a process exclusive to the centering operation and the optical sensor for centering thereby enabling contribution to an improvement in the throughput and a reduction in the device cost.
As mentioned above, Japanese Patent Publication (kokai) No. 10-303270 proposes a method for transferring a carrier-in lot unit by using the AGV With the adoption of this conveyance method, it is possible to solve the above problem about the transportation of wafers.
However, due to the large-diameter and hyperfineness of a wafer, there is a jump in the number of devices to be formed in a single wafer, requiring a long period for completing an inspection of one wafer. Moreover, the inspection of wafers in lot unit would cause the wafers after inspecting to stay in a prober (carrier) until the inspection of all of the wafers in the lot is completed thereby delaying a time for feeding the wafers in lot unit to a sequent process. Consequently, it becomes difficult to shorten TAT (Turn-Around-Time) in the production.
Therefore, by executing the following steps of: dividing the wafers one by one into a plurality of probers thereby processing the wafers at the probers in parallel; subsequently picking up the wafers after inspecting from the probers in sequence and further accommodating them in lot unit into a carrier and furthermore, and transferring the so-accommodated wafers in carrier unit to the next process, it becomes possible to shorten the TAT Then, in view of delivering wafers one by one, the AGV has to be equipped with a pincette. However, in order to allow an arm mechanism to hold the wafers one by one on the arm, it is noted that the arm mechanism requires a vacuum absorbing mechanism. For this vacuum absorbing mechanism, it is preferable in simplicity for the mechanism to employ a compressor and an ejector. However, since there exists a limitation in the power capacity of a battery forming a drive source for the compressor, on board of the AGV, it is impossible to assure a sufficient flow rate of exhaust gas necessary for the vacuum absorption.
Therefore, it is desired to provide a vacuum holding device for objects to be processed, which can assure a sufficient flow rate of exhaust gas in spite of a low-capacity battery on board of a moving body, thereby allowing the object to be absorbed in vacuum certainly.